The present invention relates to a pipettor apparatus for automatically and rapidly transferring accurate and precise multiple quantities of samples (e.g., blood serum) and reagent to the rotatable transfer disc of a centrifugal analyzer of the type disclosed in "Analytical Biochemistry", Vol. 28, pages 545-562 (1969).
More particularly, the present invention relates to a pipettor apparatus of the type described which is an improvement over the apparatus disclosed in U.S. Pat. No. 4,046,511 issued to J. Stabile on Sept. 6, 1977 and U.S. Pat. No. 3,801,283 issued to S. I. Shapiro and T. Picunko on Apr. 2, 1974.
The centrifugal analyzer of the type disclosed in the "Analytical Biochemistry" article, the disclosure of which is incorporated herein by reference, utilizes a centrifugal field to transfer sample and reagents from a series of radially aligned cavities in a rotatable transfer disc to an analyzing device. More specifically, the system is basically a series of cuvets arranged around the periphery of a rotor so that when it is spun together with the transfer disc, centrifugal force simultaneously mixes and transfers reagents and samples to the cuvets where an analysis is made spectrophotometrically.
In operation, the rotatable transfer disc is first filled with samples and reagents by suitable means such as an automatic pipettor apparatus disclosed in the above-mentioned U.S. patents. The transfer disc contains rows of cavities arranged radially therein with each cavity having an inner and outer section for reagent and sample, respectively. Each sample to be analyzed is placed individually in the outer section of a cavity and the reagent is placed in the inner section of the same cavity. The transfer disc is then taken from the pipettor and placed on a rotor in the analyzer where it is suitably indexed. As the rotor and transfer disc are accelerated, centrifugal force propels the sample and the reagent through communicating passageways to the individual cuvets within the rotor where they are mixed. The filled cuvets rapidly spin between a light source and photometric detector and the transmission of light through the cuvets, i.e., through the reacting solution, is then measured.
It is important in utilizing analyzers of the type described that the sample and reagent be introduced to the transfer disc rapidly and in accurate amounts in order to ensure accuracy of the test, to avoid wastage of expensive reagents and to reduce the time required and hence the expense of testing.
Pipettor apparatus of the type disclosed in the above-noted U.S. patents have heretofore performed satisfactorily in operation of the analyzer system but they are nonetheless subject to certain limitations. For example, the operation of these pipettor apparatus is based upon a complicated mechanical cam arrangement which is not flexible enough to permit many variations in the pipetting procedure.
It is, therefore, an object of the present invention to provide an improved pipettor apparatus for automatically and rapidly transferring accurate multiple quantities of sample and reagent to the rotatable transfer disc of a centrifugal analyzer.
A more specific object of the present invention is to provide such an improved pipettor apparatus which is far more flexible in operation when compared to similar pipettors of the prior art and which is capable of performing a number of pipetting procedures which were not possible heretofore.